Using the epidermis from the tobacco hornworm, Manduca sexta, we plan to investigate the types of RNA synthesized under two different hormonal milleux as a clue to what cellular changes occur during the ecdysone-induced switchover in commitment of these cells from producing larval cuticle to that of pupal cuticle. Since it appears that mRNA synthesis is necessary for this change, we will isolate the poly A-containing RNA's from epidermis exposed to ecdysone versus from epidermis exposed to juvenile hormone and compare them by hybridization techniques and by translation assays. Together with this we will examine carefully the protein differences between larval and pupal cuticle. Also, we are studying the differences between the nonhistone proteins in the larvally-committed epidermis and that which is pulpally-committed. Finally we will continue our studies on the specific nuclear receptors for juvenile hormone.